The present invention relates to ligands, complexes, compositions and/or catalysts that provide enhanced olefin polymerization capabilities based on a substituted pyridyl amine structure and hafnium. The invention also relates to methods of polymerization. The invention also relates to isotactic polypropylene and methods of preparing isotactic polypropylene.
Ancillary (or spectator) ligand-metal coordination complexes (e.g., organometallic complexes) and compositions are useful as catalysts, additives, stoichiometric reagents, monomers, solid state precursors, therapeutic reagents and drugs. Ancillary ligand-metal coordination complexes of this type can be prepared by combining an ancillary ligand with a suitable metal compound or metal precursor in a suitable solvent at a suitable temperature. The ancillary ligand contains functional groups that bind to the metal center(s), remain associated with the metal center(s), and therefore provide an opportunity to modify the steric, electronic and chemical properties of the active metal center(s) of the complex.
Certain known ancillary ligand-metal complexes and compositions are catalysts for reactions such as oxidation, reduction, hydrogenation, hydrosilylation, hydrocyanation, hydroformylation, polymerization, carbonylation, isomerization, metathesis, carbon-hydrogen activation, carbon-halogen activation, cross-coupling, Friedel-Crafts acylation and alkylation, hydration, dimerization, trimerization, oligomerization, Diels-Alder reactions and other transformations.
One example of the use of these types of ancillary ligand-metal complexes and compositions is in the field of polymerization catalysis. In connection with single site catalysis, the ancillary ligand typically offers opportunities to modify the electronic and/or steric environment surrounding an active metal center. This allows the ancillary ligand to assist in the creation of possibly different polymers. Group 4 metallocene based single site catalysts are generally known for polymerization reactions. See, generally, xe2x80x9cChemistry of Cationic Dicyclopentadienyl Group 4 Metal-Alkyl Complexesxe2x80x9d, Jordan, Adv. Organometallic Chem., 1991, Vol. 32, pp. 325-153 and xe2x80x9cStereospecific Olefin Polymerization with Chiral Metallocene Catalystsxe2x80x9d, Brintzinger, et al., Angew. Chem. Int. Ed. Engl., 1995, Vol. 34, pp. 1143-1170, and the references therein, all of which is incorporated herein by reference.
However, those of skill in the art of single site catalysis appreciate that there may be substantial differences in performance between different metal centers. For example, U.S. Pat. No. 5,064,802 discloses a broad category of mono-cyclopentadienyl ligand catalysts with abroad disclosure of useful metals, and U.S. Pat. No. 5,631,391 more specifically discloses that titanium metal centers offer performance advantages with respect to the same or similar ligands. Additionally, Coates, et al., Angew. Chem. Int. Ed., 2000, vol. 39, pp. 3626-3629 describes the unpredictable nature of olefin polymerization catalyst structure-activity relationships. Thus, references that describe, for example, groups 3-13 and the lanthanides, for example in U.S. Pat. No. 6,103,657, are not of adequate performance indicators of all that is within the scope of what is allegedly described. Moreover, as those of skill in the art appreciate, differences in ligand substituents typically polymerize different monomers at different performances under different polymerization conditions, and discovering those specifics remains a challenge.
One application for metallocene catalysts is producing isotactic polypropylene. An extensive body of scientific literature examines catalyst structures, mechanism and polymers prepared by metallocene catalysts. See, e.g., Resconi et al., xe2x80x9cSelectivity in Propene Polymerization with Metallocene Catalysts,xe2x80x9d Chem. Rev. 2000, 100, 1253-1345 and G. W. Coates, xe2x80x9cPrecise Control of Polyolefin Stereochemistry Using Single-Site Metal Catalysts,xe2x80x9d Chem. Rev. 2000, 100, 1223-1252 and the references sited in these review articles. See also, U.S. Pat. No. 5,026,798 that reports a mono-cyclopentadienyl metallocene for the production of isotactic polypropylene. Isotactic polypropylene has historically been produced with heterogeneous catalysts that may be described as a catalyst on a solid support (e.g., titanium tetrachloride and aluminum alkyls on magnesium dichloride). This process typically uses hydrogen to control the molecular weight and electron-donor compounds to control the isotacticity. See also EP 0622380, U.S. Pat. Nos. 4,297,465, 5,385,993 and 6,239,236.
Given the extensive research activities with respect to metallocene catalysts, there is continued interested in the next generation of non-cyclopentadienyl ligands for olefin polymerization catalysts providing attractive alternatives. See, e.g., xe2x80x9cThe Search for New-Generation Olefin Polymerization Catalysts: Life beyond Metallocenesxe2x80x9d, Gibson, et al., Angew. Chem. Int. Ed., 1999, vol. 38, pp. 428-447; Organometallics 1999, 18, pp. 3649-3670. Recently, such systems have been discovered, see, e.g., U.S. Pat. Nos. 6,103,657 and 5,637,660. For isotactic polypropylene, bis-amide catalysts have been disclosed in U.S. Pat. No. 5,318,935 and amidinate catalysts have been disclosed in WO 99/05186. See also U.S. Pat. No. 6,214,939.
There remains a need for the discovery and optimization of non-cyclopentadienyl based catalysts for olefin polymerization, and in particular for certain polymers, such as isotactic polypropylene and ethylene-alpha-olefin copolymers. For a solution polymerization methodology, this need may be acute in view of the lack of versatile catalysts for the preparation of isotactic polypropylene at commercially acceptable temperatures. Indeed, new polymer properties are disclosed herein for isotactic polypropylene, ethylene-styrene copolymers and ethylene-isobutylene copolymers.
This invention discloses surprising enhanced catalytic performances for olefin polymerization when certain combinations of ligands and hafnium metal precursors are employed. This invention also discloses surprising enhanced catalytic performances for olefin polymerization when certain metal complexes are employed in a catalyst, including 2,1 metal complexes and 3,2 metal complexes. In addition, some of the ligands employed herein are themselves novel.
In some embodiments, this invention discloses both the preferred use of a hafnium metal center and certain pyridyl-amine ligands. Such combinations lead to new ligand-metal complexes, catalyst compositions and processes for the polymerization of olefins, diolefins, or other polymerizable monomers. In particular, copolymers of ethylene and another monomer may be prepared with controlled incorporation of the other monomer (e.g., 1-octene, isobutylene, or styrene) into the polymer backbone. In some embodiments, this control is adjusted so that the olefin incorporation is considered to be high with respect to polymers currently known or commercially available. Also in particular, propylene may be polymerized into very high molecular weight isotactic polypropylene. Thus, polymers having novel, improved or desired properties may be prepared using the catalysts and processes of this invention.
More specifically, in some embodiments, the use of a hafnium metal has been found to be preferred as compared to a zirconium metal for pyridyl-amine ligand catalysts. A broad range of ancillary ligand substituents may accommodate the enhanced catalytic performance. The catalysts in some embodiments are compositions comprising the ligand and metal precursor, and optionally may additionally include an activator, combination of activators or activator package.
The invention disclosed herein additionally includes catalysts comprising ancillary ligand-hafnium complexes, ancillary ligand-zirconium complexes and optionally activators, which catalyze polymerization and copolymerization reactions, particularly with monomers that are olefins, diolefins or other unsaturated compounds. Zirconium complexes, hafnium complexes, compositions or compounds using the disclosed ligands are within the scope of this invention. The metal-ligand complexes may be in a neutral or charged state. The ligand to metal ratio may also vary, the exact ratio being dependent on the nature of the ligand and metal-ligand complex. The metal-ligand complex or complexes may take different forms, for example, they may be monomeric, dimeric or higher orders thereof.
For example, suitable ligands useful in this invention may be characterized by the following general formula: 
wherein R1 is a ring having from 4-8 atoms in the ring generally selected from the group consisting of substituted cycloalkyl, substituted heterocycloalkyl, substituted aryl and substituted heteroaryl, such that R1 may be characterized by the general formula: 
where Q1 and Q5 are substituents on the ring ortho to atom E, with E being selected from the group consisting of carbon and nitrogen and with at least one of Q1 or Q5 being bulky (defined as having at least 2 atoms). Qxe2x80x3q represents additional possible substituents on the ring, with q being 1, 2, 3, 4 or 5 and Qxe2x80x3 being selected from the group consisting of hydrogen, alkyl, substituted alkyl, cycloalkyl, substituted cycloalkyl, heteroalkyl, substituted heteroalkyl, heterocycloalkyl, substituted hetercycloalkyl, aryl, substituted aryl, heteroaryl, substituted heteroaryl, alkoxyl, aryloxyl, silyl, boryl, phosphino, amino, thio, seleno, halide, nitro, and combinations thereof. T is a bridging group selected group consisting of xe2x80x94CR2R3xe2x80x94 and xe2x80x94SiR2R3xe2x80x94 with R2 and R3 being independently selected from the group consisting of hydrogen, alkyl, substituted alkyl, cycloalkyl, substituted cycloalkyl, heteroalkyl, substituted heteroalkyl, heterocycloalkyl, substituted hetercycloalkyl, aryl, substituted aryl, heteroaryl, substituted heteroaryl, alkoxyl, aryloxyl, silyl, boryl, phosphino, amino, thio, seleno, halide, nitro, and combinations thereof. Jxe2x80x3 is generally selected from the group consisting of heteroaryl and substituted heteroaryl, with particular embodiments for particular reactions being described herein.
Also for example, in some embodiments, the ligands of the invention may be combined with a metal precursor compound that may be characterized by the general formula Hf(L)n where L is independently selected from the group consisting of halide (F, Cl, Br, I), alkyl, substituted alkyl, cycloalkyl, substituted cycloalkyl, heteroalkyl, substituted heteroalkyl, heterocycloalkyl, substituted heterocycloalkyl, aryl, substituted aryl, heteroaryl, substituted heteroaryl, alkoxy, aryloxy, hydroxy, boryl, silyl, amino, amine, hydrido, allyl, diene, seleno, phosphino, phosphine, carboxylates, thio, 1,3-dionates, oxalates, carbonates, nitrates, sulphates, ethers, thioethers and combinations thereof; and optionally two L groups may be linked together in a ring structure. n is 1, 2, 3, 4, 5, or 6.
In another aspect of the invention, a polymerization process is disclosed for monomers. The polymerization process involves subjecting one or more monomers to the catalyst compositions or complexes of this invention under polymerization conditions. The polymerization process can be continuous, batch or semi-batch and can be homogeneous, supported homogeneous or heterogeneous. Another aspect of this invention relates to arrays of ligands, metal precursors and/or metal-ligand complexes. These arrays are useful for the high speed or combinatorial materials science discovery or optimization of the catalyst compositions or complexes disclosed herein.
These catalysts comprising ancillary ligand-metal complexes or compositions comprising metal precursors and ligands and, optionally, activators are particularly effective at polymerizing xcex1-olefins (such as propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, and styrene), copolymerizing ethylene with xcex1-olefins (such as propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, and styrene), and copolymerizing ethylene with 1,1-disubstituted olefins (such as isobutylene). These compositions might also polymerize monomers that have polar functionalities in homopolymerizations or copolymerizations. Also, diolefins in combination with ethylene and/or xcex1-olefins or 1,1-disubstituted olefins may be copolymerized. The new catalyst compositions can be prepared by combining a hafnium precursor with a suitable ligand and, optionally, an activator or combination of activators. This invention discloses a novel class of catalysts and improved method for preparing isotactic polypropylene. The catalyst is useful for polymerizing a wide variety of polymerizable monomers.
In particular, a method of producing isotactic polypropylene is in a solution process is disclosed and is surprisingly tunable. In one aspect, the temperature of the solution polymerization process can be increased, which generally decreases the molecular weight, but surprisingly, while maintaining a relatively high isotacticity of the polypropylene and while maintaining a relatively high melting point for the polypropylene. In another aspect, the temperature of the solution process can be increased without the molecular weight of the polypropylene dropping so low to levels that are unacceptable for certain commercial applications.
In certain aspects, it has been discovered that certain ligands complex to the metal resulting in novel complexes. In one aspect, the 3,2 metal-ligand complexes of this invention may be generally characterized by the following formula: 
where M is zirconium or hafnium;
R1 and T are defined above;
Jxe2x80x2xe2x80x3 being selected from the group of substituted heteroaryls with 2 atoms bonded to the metal M, at least one of those atoms being a heteroatom, and with one atom of Jxe2x80x2xe2x80x3 is bonded to M via a dative bond, the other through a covalent bond; and L1 and L2 are independently selected from the group consisting of halide, alkyl, substituted alkyl, cycloalkyl, substituted cycloalkyl, heteroalkyl, substituted heteroalkyl, heterocycloalkyl, substituted heterocycloalkyl, aryl, substituted aryl, heteroaryl, substituted heteroaryl, alkoxy, aryloxy, hydroxy, boryl, silyl, amino, amine, hydrido, allyl, diene, seleno, phosphino, phosphine, carboxylates, thio, 1,3-dionates, oxalates, carbonates, nitrates, sulphates, ethers, thioethers and combinations thereof; and optionally the L groups may be linked together in a ring structure.
In another aspect, a solution process to prepare isotactic polypropylene is provided comprising adding a catalyst and propylene monomer to a reactor and subjecting the contents to polymerization conditions, where the temperature of the solution process is at least 110xc2x0 C. and polypropylene is produced that has a weight average molecular weight of at least 100,000, without a drop off in tacticity value (i.e., crystallinity index).
Thus, it is a feature of this invention to use hafnium-ligand complexes as polymerization catalysts with enhanced performance.
It is an object of this invention to polymerize olefins and unsaturated monomers with hafnium-ligand complexes. It is also an object of this invention to polymerize olefins and unsaturated monomers with compositions including substituted pyridyl amine ligands and hafnium metal precursors.
It is still a further object of this invention to polymerize olefins and unsaturated monomers with the hafnium-ligand complexes that additionally comprise an activator or combination of activators.
It is also an object of this invention to use non-metallocene group 4 complexes as polymerization catalysts for the production of isotactic polypropylene.
It is a further object of this invention to polymerize olefins and unsaturated monomers with a catalyst comprised of metal complexes comprising 3,2 ligands.
Further objects and aspects of this invention will be evident to those of skill in the art upon review of this specification.